The present invention concerns the suspension of vehicles and, more specifically, the guidance of a vehicle wheel in relation to the chassis of that vehicle, as well as control of deflection of the wheel in relation to the chassis.
It is known that a wheel is mounted on a hub, and that the hub is mounted on a wheel carrier by means of a bearing defining the axis of rotation of the wheel. Guidance of the wheel consists of making possible a displacement of the wheel carrier in relation to the vehicle to an extent sufficient for the suspension of the vehicle. At the same time, guidance of the wheel should be such that control of the path of the vehicle is ensured with the utmost care. The deflection movement sought is very wide vertically. It may be desired to permit a slight movement longitudinally, while ideally it is sought to prevent any relative transverse movement. Furthermore, the steering and camber variations that might induce all these movements have to be strictly contained, which also puts a constraint on design that the expert has to take into account.
If the plane perpendicular to the axis of rotation of the wheel is called wheel "plane," passing through the middle of the wheel, or more precisely through the center of the area of contact with the road of a pneumatic tire or non-pneumatic tire mounted on said wheel (generally referred to below as "tire"), control of the deflection movement actually means that guidance has to ensure a strictly controlled position of the wheel plane relative to the chassis.
In addition to the guidance aspect of the wheel plane, the suspension also has to ensure weight transfer of the vehicle on the wheel and control of the amplitude of movements allowed by guidance. That is the role ordinarily played by the springs and shock absorbers or parts combining the functions of spring (flexibility) and shock absorption (preventing the maintenance of oscillations).
All of the suspensions used at the present time on vehicles have the common characteristic of being rather cumbersome. The suspension arms must have a certain length for their angular movement and not be accompanied, for example, by overly great tracking variations (suspension diagrams). Even the MacPherson strut, the growing use of which is known to be due to the greater space it leaves for installing a motor power unit in transverse position, introduces some problems, including its height dimension.
Furthermore, the search for an ever better compromise between suspension comfort and handling leads to proposing so-called active or semiactive suspensions, control of which is now rendered possible by the progress of electronics. In general, that leads to making installation of the suspension on the vehicle even more cumbersome, by increasing the space occupied by springs and/or shock absorbers, not to mention adding extra elements forming the spring or shock absorber.